1. Field of the Invention
The present invention relates to an asynchronous transfer mode (ATM) switch, and more particularly to an ATM switch capable of performing the call processing and control operations corresponding to the plurality of user-network interfaces (UNI) between user terminals and ATM switches provided by a plurality of recommendation organizations.
2. Description of the Related Art
ATM switches are scheduled to be utilized in broadband integrated services digital networks (B-ISDN) and other next-generation communications networks. FIG. 10 is an example of an arrangement of B-ISDN system. In FIG. 10, ATM switches 80, 81 and 82 are interconnected by highspeed transmission channels, for example, optical fiber transmission channels 801, 802 and 803, and the ATM switches are connected to users via user lines 804, 805, 806 and 807, either directly, or through a user switch 83, which is an concentration terminal.
FIG. 11 is a block diagram of an ATM switch. An ATM switch module 800 is connected to the user or user switch via a line interface device 90. The ATM switch module 800 performs hardware switching of an inputted cell based on the header information in that cell, and routes the cell to the line interface device 90 to which it is addressed. The ATM switch also comprises a controller 50, which performs call processing control, i.e. processes and controls the flow of cells and the setting up of calls between users in the ATM switch module and line interface devices, and memory 60, which stores control data for carrying out these control operations. Furthermore, the controller 50 in the diagram is connected to the ATM switch module 800 and line interface devices 90 via wires not shown in the diagram.
FIG. 12 depicts in the form of a control block the call processing functions performed by the above-described controller 50 of the ATM switch 10. According to FIG. 12, for example, when a request is made to set up a connection from Terminal A to Terminal B, the ATM switch receives a call processing control signal (message) from Terminal A.
Then, the receiving message analyzer 51 calls up the prescribed analysis control data 61 from memory 60, and based on that data, analyzes the receiving message, i.e. determines whether or not the message can be received, and translates the message, among other processes.
Accordingly, based on the results of this analysis, call processing, such as acquisition of connection bandwidth (the establishment of a virtual path (VP) and virtual channel (VC)) and generation of charging information, is carried out in the call control processor 52. In addition, the sending message editor 53, on the basis of editing control data 62, edits the message to User B, with whom a connection is being established, and sends that message to Terminal B.
There are cases when the protocols of the UNI between Terminal A and the ATM switch, and the UNI between Terminal B and the ATM switch differ at this time. UNI stands for user-network interface (UNI), the interface between terminals and ATM switches in an ATM network. This difference in UNI protocols stems from the fact that there are a plurality of organizations recommending these ATM network UNI (for example, the telecommunications standards division of the International Telecommunications Union (ITU-T)), and since each of these organizations have different service objectives, each organization provides UNI that establish various original protocols.
When inter-user UNI are all different like this because each UNI is defined by the original protocols recommended by the various organizations, in a switched virtual channel (SVC) service, whereby users are connected to one another each time there is a call setup request, there is a risk of various trouble occurring, such as the inability to make connections between users with different UNI, or the need for users to invest additional funds to purchase new equipment for constructing networks with users with different UNI protocols. Further, there is also the risk that a connection setup request between differing UNI will be treated as an abnormal request, thereby adversely affecting the network system by generating failure and congestion.
In addition, the UNI protocols provided by each organization are periodically revised following their publication, and based on individual requests from users, separate UNI protocols are also provided. Therefore, since the practicalization of ATM networks is being pushed forward on the basis of a plurality of already-publicized recommendations, ATM switches must be controlled in accordance with a plurality of UNI protocols recommended by a plurality of recommendation organizations. That is, interworking control is required between different UNI.
Therefore, an object of the present invention is to provide an ATM switch capable of interworking between different UNIs in an ATM network.
The configuration of the present invention for achieving the above-stated object is an ATM switch, characterized in that it comprises memory for storing identification information which identifies user-network interfaces with terminals, analysis control data for analyzing a call control signal for each user-network interface, and editing control data for editing a call control signal for each user-network interface; analysis means for analyzing a first call control signal in accordance with the analysis control data corresponding to a first user-network interface identified on the basis of the identification information when the first call control signal is received from a first terminal for setup with a second terminal; call control means for performing call control based on the first call control signal analyzed by the analysis means; and editing means for editing the first call control signal to a second call control signal in accordance with the editing control data corresponding to a second user-network interface identified on the basis of the identification information.
Preferably, the memory stores interworking control data for controlling call process when an error is detected while the second call control signal is being edited based on the editing control data; and the ATM switch further comprises an interworking control means for controlling the call process based on the interworking control data when the error is detected.
For example, the first and second call control signals have a plurality of information elements, and when an information element essential during editing of the second call control signal is not included in the first call control signal, the interworking control means perform call clear.
For example, the first and second call control signals contain a plurality of information elements, and when an information element optional during editing of the second call control signal is not included in the first call control signal, the interworking control means controls to continue to edit to the second call control signal. preferably, the interworking control data can be customized.